Russian smugglers are ignoring economic sanctions on North Korea and delivering petroleum and other supplies, The Washington Post reports.

The United Nations Security Council on Monday approved new economic sanctions on North Korea in an attempt to force negotiations with leader Kim Jong Un over the country's nuclear weapons program.

Some Russian companies, however, continue to conduct trade with North Korea. Around the time that China's state-owned petroleum corporation ended fuel shipments to the country, officials noticed a dramatic increase in tanker traffic from the Russian port city of Vladivostok and the North Korean port of Rajin.

"As the Chinese cut off oil and gas, we're seeing them turn to Russia," an unnamed senior official said to have knowledge of smuggling operations told the paper. "Whenever they are cut off from their primary supplier, they just try to get it from somewhere else."

"Russia is now a player in this realm," Anthony Ruggiero, former Treasury Department official and now a senior fellow working with the think tank Foundation for Defense of Democracies, told the Post. "The Chinese may be fed up with North Korea and willing to do more to increase the pressure. But it's not clear that the Russians are willing to go along with that."

Last month, the Treasury and Justice Departments announced legal measures against Russian nationals accused of working with North Korea to circumvent the international sanctions. Court documents from this reveal "a web of alleged front companies established by Russian citizens for the specific purpose of concealing business arrangements with Pyongyang," according to the Post's Joby Warrick.

One company, Velmur, is officially a real estate company in Singapore, but Justice accused it of "facilitating the laundering of funds for North Korea financial facilitators and sanctioned entities," in a complaint filed last month, which notes that Velmur lacks a headquarters, offices and a website, and "bears the hallmarks of a front company."

Velmur bought close to $7 million worth of diesel from Russian supplier IPC this year, the money for which were wired to the company by North Korean operatives in U.S. dollars.

"The investigation has concluded that North Korea was the destination" of the diesel, the Justice Department notes. "As such, it appears that Velmur, while registered as a real estate management company, is in fact a North Korean financial facilitator."